Modern alternators for motor vehicles are compact pieces of equipment in which the control and regulating devices are integrated.
It is the brush-holder associated with the collector of the rotor which most often supports the device for regulating the power of the current produced by the alternator, as well as the various anti-parasite means, such as selfs and capacitors.
These active or passive electronic components must be isolated from the severe work conditions under the bonnet of the engine (temperature, vibrations, dust) by a protective housing which is relatively complex to produce.
In order to eliminate this disadvantage, European patent application EP0750388 A1 by the company VALEO EQUIPMENTS ELECTRIQUES MOTEUR proposes to provide the protection of an anti-parasite capacitor directly by over-moulding around the component.
European patent application EP1058369 A1 by the same company shows the arrangement of a semiconductor control component of the “ASIC” type in a brush-holder by implementing a wire bonding technique which has the advantage of isolating the control component from the mechanical and thermal stresses which are sustained by the brush-holder.
In the case of a control circuit which is interfaced with a serial bus of the “LIN” type (acronym for “Local Interconnect Network”), the control line may be subjected to radio-electric disturbances which create operating faults.
On regulators of this type which are sold, with an input capacity of 220 pF for example, operating faults are found starting from injection of disturbance of approximately 10 mW in DPI (an acronym for Direct RF Power Injection).
However, motor vehicle manufacturers require alternators to have strong immunity to radiofrequency disturbances, whilst retaining good operating reliability.
If a single filtering capacitor in parallel is used, the reliability is relatively good, but the immunity is relatively low.
If one to three components are integrated, by an over-moulding technique, such as that demonstrated by application EP0750388 A1, the immunity can be improved, but the components have low tolerance to the injection temperatures and pressures, even with protective caps, to the detriment of reliability.
In the brush-holders of the state of the art of the latest generation, the components are implanted after the over-moulding, but the implantation of more than three components is difficult to carry out.
There is therefore a need fir a new-generation brush-holder which integrates a control and regulating device which has strong immunity to radio-frequency disturbances, and the structure and production method of which guarantee good operating reliability.
For reasons of economies of scale, it is preferable for the technical solution to be suitable for different types of regulators and different connections.